The Door Into Summer

A book by Robert Heinlein about an engineer called Dan who designs household robots. After his business associates cheat him, Dan decides to take the "cold sleep" with his cat Petronius Arbiter, and wakes up in the year 2001. He discovers that his old robots are being produced and marketed under his own name, and has to travel back in time to find out why.

In this story by Robert Heinlein, a man (Dan Davis) is cryogenically frozen and wakes up thirty years in the future, only to discover that many of his inventions are quite famous. The only problem is that he doesn't remember inventing them. The last thing he remembers is being sent to the future via the long sleep, courtesy of his treacherous business partners. If he had never even written them down, how could they be here? With this and other questions in his mind, Dan begins to search for answers. The answers he finds raise only more questions. The patents were registered to one D. B. Davis.

After accidentally hearing about time travel, Dan decides that the answers to his problems must lie in the past. So, he resolves to travel back into the past and find out what happened while he slept. There is only one problem with all this: time travel is classified and the only one who can send him to the past is an old physicist who'd rather drink and talk about his life than engage in scientific studies.

The Door Into Summer was first published in 1956 in The Magazine of Fantasy and Science Fiction and was published the next year as a book by Doubleday.

The Door Into Summer is one of Heinlein's more prophetic stories. The main character, Dan Davis, is a sort of edisonian inventor/engineer with a talent for thinking out neat gadgets that is probably only rivaled by Heinlein himself.

In the course of the story, Dan takes us through the engineering needed to invent a dictation (speech to text, that is) machine, computer aided drafting, the water bed and, of course, the household robot. In addition, we peripherally see the hospital delivery robot, the automatic teller machine and assorted minor gizmos. Few stories in the entire annals of science fiction contain so many glimpses of the future that actually came true.

The plot is, for a time travel story, unusually straightforward. Dan invents his way past his problems and, eventually, gets the girl of his dreams.